#include<bits/stdc++.h>
using namespace std;
int n, k;

bool check(vector<double>& v, double avg) {

    double sum = 0, num = 0;
    int cnt = 0;
    for (auto& i : v) {
        sum += i;
        num++;

        double av = sum / num;

        if (avg <= av) {
            cnt++;
            sum = 0;
            num = 0;
        }
    }

    return (cnt >= k);
}

signed main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);


    cin >> n >> k;

    vector<double>v(n);
    for (auto& i : v)cin >> i;

    double l = 0, r = 10000;

    double ans = 0;
    for (int i = 0; i < 60; i++) {
        double md = (l + r) / 2.0;
        if (check(v, md)) {
            ans = md;
            l = md;
        }
        else r = md;
    }

    cout << fixed << setprecision(12) << ans << "\n";
return 0;
}